Pressure relief valve

Abstract

A pressure relief valve includes a valve body having an axial inlet port and a lateral outlet port, with an enlarged bore extending between such ports. A valve bonnet attached to the valve body slidably guides a poppet for movement between closed and open positions for closing and opening the inlet port. A seal ring positioned in the bore adjacent the inlet port sealingly surrounds the poppet in its closed position. The seal ring is axially compressed between a retainer ring and a backup surface, and a ring nut threaded in the bore compressively engages the retainer ring. The ring nut is located entirely on the inlet port side of the outlet port so it does not inhibit flow to the outlet port when the poppet is open. A poppet guide bore in the bonnet extends inwardly from a bonnet end surface, and a pair of concentric recesses of different diameters also extend into the bonnet from the end surface. One recess receives a seal ring positioned in surrounding sealing relationship with the poppet, and the other recess receives a push-in retainer for retaining the seal ring in its recess. A small diameter stem on the poppet extends into a bonnet spring receiving bore and has a rounded end received by a conical recess in a guide disc. Close fitting cylindrical locating surfaces are used for providing accurate concentricity between the bonnet and body, and between the retainer ring and the bore.